A known door lock apparatus for a vehicle is disclosed, for example, in JP2004124687A. According to the door lock apparatus disclosed, a locked state and an unlocked state of a vehicle door relative to a vehicle body are switched in a state where the vehicle door is retained in a closed state relative to the vehicle body by means of a latch mechanism. In the unlocked state, the vehicle door can be opened, i.e., the closed state of the vehicle door can be cancelled, by an operation of a door handle. In the locked state, the vehicle door cannot be opened, i.e., the closed state of the vehicle door cannot be cancelled, by the operation of the door handle.
When an inside handle is operated one time in the locked state of the vehicle door, for example, a cancel lever is operated via an open operation lever and an open lever. Then, a link member moves on a lift lever by means of an operating force transmitted from the open lever and the cancel lever. At this time, the lift lever is not operated and therefore the closed state of the vehicle door retained by the latch mechanism is not cancelled.
On the other hand, a locking lever that receives an operating force via the link member and an inside locking lever is movable from a locked position to an unlocked position because of a deformation of a spring. When the inside handle is returned to its initial position, the state where the link member is positioned on the lift lever is cancelled, thereby obtaining the unlocked state of the vehicle door.
When the inside handle is further operated one more time in the aforementioned state, the lift lever is operated to thereby cause a cancellation of the closed state of the vehicle door that is retained by the latch mechanism.
A transmission path of the operating force via the open operation lever and the open lever when the locking lever is moved from the locked position to the unlocked position by an operation of the inside handle is constituted by the cancel lever, the link member, and the inside locking lever. In this case, since the transmission path is constituted by three members, the transmission efficiency of the operation force may be reduced, which may lead to deterioration in the operation feeling of the inside handle.
Lately, the door lock apparatus provided at the vehicle door not equipped with a lock knob that links to a function of the inside locking lever, i.e., a knob-less door, has also been proposed. The inside locking lever is not necessary for such door lock apparatus. However, even when the door lock apparatus is applied to such type of door, the aforementioned transmission path is constituted by two members, which may still lead to the decrease in the transmission efficiency of the operation force of the inside handle.
A need thus exists for a door lock apparatus for a vehicle which is not susceptible to the drawback mentioned above.